Recently, electronics apparatuses having smaller size have been manufactured, and accordingly, smaller size and higher capacity for a cell as a power source have been highly desired. Various factors such as the material and manufacturing method of a primary cell and a secondary cell have been examined. Particularly, as described in Laid-open Japanese Patent Application No. (Tokkai sho) 55-155470, Laid-open Japanese Patent Application No. (Tokkai sho) 60-127661, Laid-open Japanese Patent Application No. (Tokkai sho) 61-135055, Laid-open Japanese Patent Application No. (Tokkai hei) 2-158055, and Laid-open Japanese Patent Application No. (Tokkai hei) 3-263757, the examination of the manufacturing method and the fact that the manufacturing method affects cell capacity have been reported.
In conventional methods for manufacturing a paste, a poor part was created by discontinuity in the paste in coating due to the undispersed agglomerates contained in an active material paste, and therefore the yield was decreased. Also, an electrode after coating and drying had a rough surface, and many protruding grains were observed. When a cell was manufactured by using an electrode that contains many such undispersed agglomerates, and a cycle test was repeated, deterioration in discharge capacity was severe, and the deposition of a reactant that includes such protruding grains was also seen. Also, when using an active material paste that has many agglomerates, the weight of the film coating a current collector was not uniform, and an agglomerate part was separated from a base material, resulting in remarkable deterioration in discharge capacity and many variations in cell capacity. Therefore, an improvement in a method for manufacturing an active material paste has been desired.